问题:

This doesn't work:

if(document.getElementById("iframe").innerHTML==''){

Is there a safe browser reliable way to check an iframe if its empty or not?

Thanks

回答1:

Well if you can use jQuery, check it's length property. This is cross-browser compatible. If it's zero, it doesn't exist. Something like this:

if(!$("#iframeid").length) {
    // iframe doesn't exist
}

EDIT:

After seeing your comments on your question:

If you want to check if no page loaded inside iframe, and the iframe is not cross-domain you could check for the existence of the body tag inside of the iframe. If it exists, then something loaded.

Something like this:

if($("#iframeid").contents().find("body").length) {
    // some html page loaded in iframe
}

If the iframe is cross-domain, you will be blocked by the same-origin policy. Otherwise this will work.

回答2:

Check the frame's contentDocument property. IE 7 and earlier support the contentWindow property instead, but there is a simple cross browser example at http://www.w3schools.com/jsref/prop_frame_contentdocument.asp.

A less-reliable method but might be what you want... check the src property.

You can read about other frame properties at http://www.w3schools.com/jsref/dom_obj_frame.asp